To improve the fire accuracy of air-defense projectiles,taking a type of air-defense guided projectiles with canard control as an object,the application process of trajectory prediction guidance(TPG)and modified proportional navigation guidance(MPNG)is studied in terms of the properties of air-defense projectiles.Based on the 3D trajectory model containing wind,an analytical model for trajectory prediction and the corresponding algorithm for estimating time-to-go are proposed,both of which are of good accuracy.According to the bias vector between the projectile and the future position of maneuvering target,a simple expression of acceleration command for MPNG is derived.Theoretical analysis and simulation results indicate that both of TPG and MPNG are satisfactorily effective under some conditions.For different control quantities and flight ranges,the TPG can be applied to the terminal phase of trajectory while the MPNG is more appropriate for the initial phase and mid-course.Both of the accuracy and stability requirements can be attained.